How can a vertex have a normal?
The vertex normals will be the average of the adjacent faces' normals.
Look at the lower-right corner of the ear in each of the two head images showing &quot;face&quot; vs &quot;vertex&quot; normals:

Notice that the face normals from the image on the left, about the lower-right vertex, are moved and redrawn from that vertex on the image to the right.
I am not an expert in cgi but it is safe to assume that all normal vectors are the same size. A unit vector about the vertex can be found by adding the vectors tip-to-tail and dividing by the length. This unit vector would then be scaled up by whatever display length the user selected.